Heat exchange system for air conditioner



.Feb. 11, 1958 E. P. wHlTLow HEAT EXCHANGE: SYSTEM FOR AIR CONDITIONER 5Sheets-Sheet 1 Filed Oct. 8, 1951 IN V EN TOR.

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Feb. 11, 1958 E. P. wHlTLow v2,823,015

HEAE` EXCHANGE SYSTEM FOR AIR CONDITIONER 5 Sheets-Sheet 2 Filed Oct.8v, 1951 INVENTOR.

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Feb. 1l, 1958 E.'P. wHrrLow 2,823,015

HEAT EXCHANGE SYSTEM FOR AIR CONDITIONER Filed Oct. 8, 1951 3Sheets-Sheet 3 United States IPatent vC HEAT EXCHANGE SYSTEM FOR AIRCONDITIONER Eugene P. Whitlow, Evansville, Ind., assignor, by mesneassignments, to Arkla Air Conditioning Corporation, a corporation ofDelaware Application ctober 8, 1951, Serial No. 250,369

4 Claims. (Cl. 257-3) The present invention relates to air conditioningand more particularly to apparatus for heating, cooling or dehumidifyingthe air in an enclosure as required.

A conventional type of air conditioning apparatus comprises a coolingelement and a fan for circulating vair from the enclosure to beconditioned into heat exchange relation with the cooling element andthen back to the enclosure. The air is cooled by the cooling element anda portion of the air directly contacting the element is cooled below itsdew point to precipitate moisture and thereby dehumidify the air. If theair conditioning apparatus is controlled by the temperature in theenclosure, dehumidiication only occurs when coolingis required. In manylocalities where the humidity is normally high, such limiteddehumidication is not sucient to produce a comfortable atmosphere in theenclosure.

Reheat schemes have heretofore been provided with temperature controlledair -conditioning units to reheat the air after it has been dehumidiedby cooling to cause the apparatus to operate for longerperiods. The heatfor such reheating of the cooled air may be supplied from any suitablesource such as wasteheat rejected from the refrigeration system. Adiiticulty with such reheat schemes has been to produce the greatestpossible dehumidication with least possible cooling or, in other words,a maximum ratio of latent to sensible heat removal and to control therate of reheat in accordance with requirements. The .cooling anddehumidifying requirements may vary from hour tohour and from day to dayand usually some degree of cooling :is Vrequired when the humidity ishigh. However, the cooling requirements may be so small that very shortperiods of operation of the refrigeration system are sufficient to coolthe air but continuous operation of the apparatus is necessary to meetthe humidity requirements. In an ideal reheat arrangement therefrigeration system would operate continuously at varying cooling anddehumidifying conditions and adjust the ratio of latent to sensible heatremoval to exactly balance the cooling and dehumiditying loads until thecooling load approaches zero at which time the air leaving ywould havethe same temperature as air entering the apparatus. Suchl an idealreheat arrangement has not been economically feasible. l

One reheat scheme for approaching this ideal condition comprises arun-around? coil arrangement having a precooling section in front of theevaporator, a reheat sectionv behind the evaporator in the directionqofair flow and a pump for continuously circulating arheat eX- changemedium through the coil sections successively. ln operation theprecooling coil removes heat from the relatively warm air to reduce itstemperature before -it contacts the cooling element and the reheat coildelivers the absorbed heat back to the relatively cold air to increaseits temperature after it leaves the cooling element. With such anarrangement the precooling coil will cool the air from room temperatureto some tem- ICC perature approaching its dew point so that most of thecooling by the cooling element produces dehumidication but thearrangement inherently cannot compensate for the sensible coolingnecessarily accompanying dehumidication by the cooling element.Therefore, the air being conditioned will be cooled and its temperaturewill gradually `fall even though a high ratio of latent to sensible heatremoval is attained to dehumidify at a high rate.

One of the objects of the present invention is to provide a heatexchange system in an air conditioning unit for heating the air to beconditioned or reheating dehumidified air to its initial temperature andmaintain the unit in continuous operation until the humidity isdecreased to the desired level.

Another object is to provide a reheat arrangement of the type indicatedfor precooling the air prior to dehumiditication and utilizing the heatremoved from the air for reheating the air after dehumidification toreduce the load on the refrigeration system and dehumidify the air at anincreased rate.

Another object is to remove heat from the air prior to dehumidiiication,deliver the removed heat back into the air after dehu-midification andsupply additional heat in accordance with requirements to maintain theair in the enclosure at substantially the same temperature.

Another object is to provide a reheat arrangement of the type indicatedwhich is adapted to vary the ratio of latent to sensible heat removal inaccordance with requirements.

Still another object is to provide a reheat arrangement of the typeindicated which utilizes waste heat from the refrigeration system tosupply the additional heat necessary to maintain the air leaving theapparatus at the same temperature as the air entering the apparatus.

These and other objects will become more apparent from the followingdescription and drawings in which like reference characters denote likeparts throughout the several views. It is to be expressly understood,however, that the drawings are for the purpose of illustration only andnot al definition of the limitation of the invention, reference beinghad for this purpose to the appended claims. In the drawings:

Fig. l is a side elevational view of an air conditioning apparatusincorporating the heat exchange system of the present invention.

-Fig 2 is an enlarged sectional View of the selective valve means forshifting from heating to cooling or vice versa.

Fig. 3 is a view of an air conditioning unit similar to Fig. 1 andshowing a heat exchange system utilizing waste heat from therefrigeration system to reheat the air cooled and dehumiditied by thelatter.

Fig. 4 is adiagrammatic view of the cooling element of a conventionalair conditioner and indicating the percent of latent heat removal for atypical condition.

Fig. 5 is a diagrammatic view of the improved heat exchange system ofthe present invention for dehumidifying air at a higher rate andmaintaining the air leaving the apparatus at thensameVV temperature asthe air entering the apparatus.

Referring to the drawings, the invention is shown applied to yan airconditioning unit 7 for conditioning air in an enclosure 8. The airconditioning unit 7 comprises a conduit 9 for receiving air from theenclosure 8, a conditioning chamber 10, and a conduit 11 for deliveringair back to the enclosure. The air to be conditioned is circulated inthe direction indicated by arrows through the enclosure 8, conduit 9,conditioning chamber 10 and conduit 11by means of an electric motoroperated blower 12.V As the air flows through the conditioning chamberit is conditioned by elements mounted therein comprising a filter 13, acooling element 14, and a humidifier 15. The cooling element 14constitutes the evaporator of a heat operated absorption refrigera Vtionsystem operated by steam from a suitable source such as the boiler 16and controlled by a selective valve means 17.

The heat operated refrigeration system is preferably of the typeillustrated and described in United States Letters Patent 2,282,503 ofAlbert R. Thomas et al. issued May 12, 1942, entitled Refrigeration.Such an absorption refrigeration system operates in a partial vacuum andutilizes water as a refrigerant and a salt solution as an absorbent.Sufce it to state herein that the refrigeration system comprises agenerator 1.8, a condenser 19, evaporator 14, absorber 20 and heatexchanger 21 intercon nected to provide a closed circuit. The generator18 has a series of upright tubes 22 connected at their lower ends to aninlet chamber 23 for absorption solution and con nected at their upperend to a separating chamber 24. Surrounding the tubes 22 is a shell 25providing a heating chamber 26 therebetween.

Steam is supplied to the heating chamber Z6 from the boiler 16 throughthe selective valve means 17 and conduit 27 and heat is transferred fromthe steam through the tubes 22 to the absorption solution therein toexpel refrigerant vapor therefrom. The refrigerant vapor rises throughthe tubes 22 at considerable velocity and raises the absorption solutionat the sides of the tubes by a climbing film action. The refrigerantvapor ows from the separating chamber 24 to the condenser 19 through aconduit 23 and liquefied refrigerant flows from the condenser throughany suitable iiow control arrangement such as the orifice device 29 tothe evaporator or cooling element 14. The orifice device is describedand claimed in the United States Letters Patent to N. E. Berry 2,563,575issued August 7, 1951, and entitled Absorption Refrigera tion, andoperates to permit concurrent iiow of liquid refrigerant andnon-condensable gases from the condenser 19 to the evaporator or coolingelement 14 while maintaining a difference in pressure therebetween. Thecooling element or evaporator 14 comprises a plurality of finned tubes14a connected between spaced headers 30 and through which the liquidrefrigerant flows by gravity and is evaporated by a heat exchangethrough the walls of the tubes from the air. Refrigerant vapor flowsfrom the evaporator or cooling element 14 to the absorber 20 throughpassages or headers 30.

Absorption solution weak in refrigerant or, in other words, aconcentrated salt solution, flows by gravity from the separating chamber24 to the top of the absorber 2t) in a path of iiow including theconduit 31, heat exchanger 21 and conduit 32. The solution absorbs therefrigerant vapor in the absorber 20 and this solution strong inrefrigerant, or, in other words, dilute salt solution, ows by gravityfrom the bottom of the absorber 20 to the inlet chamber 23 at the bottomof the generator 18 in a path of ow including the conduit 33, heatexchanger 21, conduit 34, leveling vessel 35 and conduit 36. Theabsorption of refrigerant Vapor in absorber 20 maintains a relativelylow pressure and temperature in the evaporator 14 to produce arefigerating effect and the low pressure in the evaporator and absorberis maintained by liquid columns in the conduits 32 and 33.

The absorber 20 and condenser 19 are cooled by cooling water from anysuitable source such as a city water main or cooling tower. The coolingwater enters the cooling coils 37 in the absorber 20 through a conduit38 and is discharged from the absorber through a conduit 39 connected tothe condenser 19. Cooling water is discharged from the condenser 19through a conduit 40 for flow back to the cooling tower or to a suitablewaste pipe. Thus, the cooling water passes through the absorber 20 andcondenser 19 in succession to cool both of the heat rejecting parts ofthe refrigerating system.

In accordance with the present invention, a heat exchange system in theform of a closed run-around circuit is provided which is adapted to heatthe air during winter operation or to reheat dehumidied air from thecooling element 14 during summer operation. The closed heat exchangesystem comprises a heat exchange element or section 42 in front of thecooling element 14 in the conditioning chamber 10, a second heatexchange element or section 43 behind the cooling element 14 in thedirection of air flow and a third heat exchange element 44 remote fromthe cooling element 14 and out of the path of air flow. Each of the heatexchange sections 42 and 43 is illustrated in the form of serpentinecoils and preferably one end of a series of such coils is connected by aheader 45 and the opposite ends of the coils are connected by a header46. The heat exchange section 44 is also in the form of a coil 47enclosed in a heating chamber 48 and connected at one end to the outletAfrom the coil 42 by a conduit 49 and connected at its other end to theinlet to the coil 43 by a conduit 5t). The outlet from the coil 43 isconnected to the inlet of the coil 42 by a conduit 51 to provide aclosed circuit. The closed heat exchange system contains a fluid `suchas water which is circulated by means of a pump 52 in the directionshown by arrows. The coils 42 and 43 are connected and arranged in theclosed heat exchange system to ow the heat exchange fluid in a directioncountercurrent to the direction of air flow through the conditioning7chamber 10 as shown in Figs. l and 5.

The selective valve means 17 illustrated in detail in Fig. 2 is the sameas that described and claimed in a copending application of LowellMcNeely, Serial No. 44,381, tiled August 14, 1948, now Patent No.2,581,122, granted January l, 1952, and entitled Air Conditioning. Theselective valve means comprises a chamber 53 having an inlet port 54connected to the boiler 16 by a steam pipe 55, an outlet port 56connected to the heating chamber 26 of the generator 18 by conduit 27,an outlet port 57 connected to the heating chamber 48 of the heatexchange section 44 by a conduit 58 and a valve element 59 forselectively closing one of the ports 56 or 57 and opening the otherport, respectively. The valve element 59 is mounted on a shaft 60 havingone end projecting through the chamber 53. A crank arm 61 on the end ofthe shaft 60 is connected by a link 62 to the crank of a motor 63 .forshifting the valve element from one to the other of its two positions.Thus, when the valve element 59 is in the position illustrated in Fig.2, steam is delivered from the boiler to the generator 18 of therefrigeration system and when the valve element is shifted to close theport 56, steam is delivered from the boiler to the heating chamber 48 ofthe heat exchange system.

The selective valve 17 is also adapted to supply heat to the closed heatexchange system simultaneously with the supply of heat to the generator8 of the refrigeration system. For this purpose the selective valve 17is provided with a by-pass conduit 64 connecting the chamber 53 to theconduit 58 around the valve element 59. An orifice 65 is provided in theby-pass conduit 64 to limit the amount of steam which may flowtherethrough and a second throttling valve 66 is provided in the by-passconduit for modulating the flow of steam therethrough. The by-passconduit 64 has a depending loop 67 for receiving condensate from theheating chamber 48 and a drain valve 68 connected to the bottom of theloop. The depending loop 67 provides a liquid trap to block the .conduitwhen the drain valve 68 is closed and open the conduit for the flow ofsteam therethrough when the drain valve is open.

Operation of the air conditioning unit 7 may be controlled manually orby any suitable control means such as that disclosed in the McNeelyapplication Serial No. 44,381 referred to above. For example, aselective controller 70 may be provided having a lever 71 for manuallyselecting heating or cooling with thermostatic switch means for startingand stopping the selected system, or a thermostatic switch means may beprovided for automatically shifting from heating to cooling.Dehumidication may be controlled by a humidistatic switch 72 forinitiating operation of the refrigeration system when the temperature inthe enclosure is satisfactory but the humidity is high. Such controlmeans are shownV in the McNeely application referred to above and inother patents but are not essential to the present invention except toinitiate operation of the heating and cooling systems as required.

However, the regulation of the amount of additional heat supplied to theheating system during a reheating operation is a feature of the presentinvention. As illustrated in'Fig. l, this regulating means comprises athermostat having a bulb 73 subjected to thetemperature of thecirculating air, a bellows 74, see Fig. 2, connected to operate thethrottling valve 66 in the by-pass conduit 64 and a spring 75 opposingthe movement of the bellows 74. The bulb 73 of the thermostat may belocated anywhere in the path of the circulating air and is adapted tooperate the valve 66 to supply heat to the heating system at the raterequired to reheat the dehumidified air to the temperature of the airentering the conditioning unit. It will be understood that thecontroller 70 will operate through the motor 63 to actuate the selectivevalve means 53 for heating or cooling as required and that thehumidistatic switch 72 will initiate operation of the refrigerationsystem, blower 12 and circulating pump 52 when dehumidication withoutcooling is desired. One form of the invention having now been describedin detail, the mode of operation is explained as follows.

When it is desired to heat the enclosure S the selective valve element59 is shifted from the position illustrated in Fig. 2 to close port 56and open port 57 operation of blower 12 is initiated to circulate air inthe enclosure 8 through the conditioning chamber in the directionindicated by arrows; operation of pump 52 is initiated to circulate theiluid in the closed heat exchange system and through heat exchange coils43 and 42 in a direction counter-current to the direction of air flow;and a heating means is initiated to heat the boiler 16 and generatesteam. As explained above, such functions may be performed manually orautomatically through a suitable control means such as the thermostaticcontroller 70 illustrated in the enclosure 8 to be conditioned. Steamfrom the boiler 16 then ows through the steam pipe 55, chamber 53 yofselective valve means 17, port 57 and conduit 58 to the heating chamber48 of the heat exchange system. Fluid in coil 47 of the heat exchangesection 44 is heated by the exchange of the latent heat of the steamcondensing on the coil and llowing through the walls thereof'. Theheated fluid is continuously circulated by pump 52 through the conduit5u, heat exchange coil section 43, conduit 51, heat exchange coilsection 42 and conduit 49 back to the coil 47 of the heat exchangesection 44. Coil 42 preheats the air flowing through the conditioningchamber 10 and coil 43 further heats the air to its nal temperature. Itwill be noted that the fluid in the closed heat exchange system at alltimes flows in a direction countercurrent to the direction of air ow sothat there will be a temperature gradient between all portions of theheat transfer sections 42 and 43 and the air flowing in heat exchangerelation thereto. The apparatus continues to operate in the mannerdescribed until the air in the enclosure 8 is increased to the desiredtemperature at which time the heating period is terminated. Thus, theapparatus operates intermittently to maintain a substantially constanttemperature in the enclosure 8 and the periods of operation vary inaccordance with the load as affected by the outside temperature.

When it is desired to cool the enclosure 8 the selective valve element59 is shifted to the position illustrated in Fig. 2 to open port 56 andclose port 57. The heating means for the boiler 16,- the pump 52 and theblower 12 are initiated as previously explained. Steam then flows fromthe boiler 16 to the generator 18 of the heat operated absorptionrefrigeration system through the steam pipo 5S, chamber 53' and Vport S6of thevselective .valve means 17 and conduit 27 tothe heatingchamber'26. Heat applied to the generator 18 supplies refrigerant to thecooling element 14 and absorbent to the absorber 20. Thev high ainity ofthe refrigerant for absorbent reduces the vapor pressure and temperatureof evaporation of the refrigerant in the evaporator or cooling element14.

Air circulated by the blower 12 from the enclosure 8l When the coolingload is low and the humidity is high, the periods of operation of therefrigeration system maynot be enough to sufficiently dehumidify the airfor comfort conditions. In other words, when the temperature in theenclosure 8 is satisfactory, it is many times desirable to dehumidifythe air to reduce the humidity. When dehumidication without cooling isdesired, the refrigeration system is initiated either manually or bymeans of a humidistatic switch 72.. Simultaneously, operation of thepump 52 and blower 12 is initiated and the drain valve 68 is opened todrain the liquid trap in the by-passk conduit 64 around the selectivevalve element 59. Steam is then supplied from the boiler 16 to both thegenerator 18 of the refrigeration system and heating chamber 48 of theheat exchange element 44, the steam owing to heating chamber 48 fromchamber 53 of the selective valve means 17 through the by-pass conduit64 to conduit 58.

Air flowing through the conditioning chamber 10 is iirst precooled bythe heat exchange coil 42 to reduce its temperature prior to its contactwith the cooling element 14 of the refrigeration system. The air nextcontacts the relatively cold tubes 14a of the cooiing element 14whichreduces the temperature of a large portion of the air below its dewpoint to precipitate moisture therefrom and' thereby dehurnidify theair. The relatively cold dehumidihed air then contacts the reheat coilsection 43 of the closed heat exchange system which reheats the air toits initial temperature. The heat delivered by the reheat coil section43 is supplied by the huid -circulating in the closed heat exchangesystem. All of the heat removed from the air by the precooling coilsection 42 is contained in the circulating fluid and is delivered backto the air by the reheat coil section 43'andonly an amount of heat issupplied to the uid by the heat exchange coil 47V that is necessary tocompensate for the sensible heat removed by the cooling element 14 ofthe refrigeration system. Therefore, with the closed heat exchangesystem of the present invention, the load on the refrigeration system isdecreased by the amount of cooling performed by the precooling coil 42.

Usually when dehumidiication is required, some cooling is also necessaryand the ratio of latent to sensible heat removal varies from hour tohour and from day to day. Thus, the amount of additional heat suppliedto the circulating iluid in the closed heat exchange system must bevaried in accordance with particular operating conditions. To this end,steam is supplied from chamber 53 of thev selective valve means 17 tothe heating chamber 48 of the heat exchange element 44 at a ratecontrolled by the orifice 65 and throttling valve 66 in by-pass conduit64. The oriiice 65 will supply steam to the heatingl chamber 48 at amaximum rate required for reheat and the throttling valve 66 is adjustedin accordance with operating conditions to vary the amount of steamsupplied. To

7 this end, bulb 73 of the control thermostat responds to thetemperature of the circulating air and operates through the bellows 74to adjust the throttling valve 66. At a lower temperature limit, forexample, 79 F., the throttling valve 66 will be wide open and at anupper temperature limit, for example, 82 F., the throttling valve willbe closed. At some temperature between 79 and 82 F. an equilibriumcondition will be reached at which the throttling valve 66 will supplythe required amount of additional heat to reheat the air to its originaltemperature. The apparatus continues to Operate in the manner describedto dehumidify and reheat the air until the humidity in the enclosure 8is decreased to a desired value and the throttling valve 66 isconstantly adjusted during such dehumidication to vary the amount ofheat added. As in the case of heating as explained above, the iluidcirculating in the closed heat exchange system always flows in adirection countercurrent to the direction of air ilow so that thecoolest air contacts the coolest portion of the precooling coil section42 and the hottest air contacts the hottest portion of the reheat coil43 to provide a temperature diierential between all portions of the coilsections and the air flowing therethrough.

The improvement in the ratio of latent to sensible heat removal andcontrol of the outlet air temperature is shown in the diagrammatc viewsillustrated in Figs. 4 and S of the drawings. Fig. 4 illustrates theeffect of the cooling element 14 of a standard absorption refrigerationsystem in dehumidfying the air at one typical set of operatingconditions. It will be noted that air enters the cooling element 14 at adry bulb temperature of 80 F. and leaves the unit at a dry bulbtemperature of 61 F. and that the latent heat removal or amount ofcooling used for dehumiditication is 28%. Fig. 5, on the other hand,illustrates applicants reheat arrangement ap plied to the coolingelement of the same standard refrigeration system for conditioning airunder the same operat ing conditions and shows a decrease in thesensible heat removal from 41,500 B. t. u. to 29,555 B. t. u., and anincrease in the latent heat removal from 16,100 B. t. u. to 21,750 B. t.u. r an increase from 28% to 42.4% latent heat removal by coolingelement 14 and an overall latent heat removal of 100%.

With the arrangement illustrated in Fig. 1, a portion of the steamgenerated in boiler 16 is bled through the by-pass conduit 64 to theheating chamber 48 of the heat exchange element 44 With a resulting lossto the capacity of the refrigeration system. Although this loss to therefrigeration system may be avoided by providing an additional heaterfor the boiler 16, such additional heat constitutes a loss in theoverall operating eciency of the air conditioning unit. In accordancewith the arrangement illustrated in Fig. 3 of the drawings, waste heatfrom the refrigeration system is utilized to provide the additional heatto the heat exchange reheat system.

The air conditioning unit illustrated in Fig. 3 is substantiallyidentical with that illustrated in Figs. l and 2 except that anadditional heat exchange element 80 is provided in the circuit of theclosed heat exchange system between the sections 42 and 43 in thedirection of uid ow, the by-pass conduit 64 yof the selective valvemeans 17 is eliminated, the cooling water from the condenser 19 iscaused to flow in heat exchange relation with the heat exchange element80 and a different control arrangement 81 is provided for regulating theamount of heat added to the fluid in the heat exchange system. The heatexchange element 80 is substantially identical with the heat exchangeelement 44 and comprises a coil 82 and a heating chamber 83 enclosingthe coil. The inlet end of the coil 82 is connected to the outlet fromthe coil section 42 by a conduit 49 and the outlet from the coil isconnected to the pump 52. Conduit 40 for the cooling water fromcondenser 19 is connected to the bottom of the heating chamber S3 and aconduit 85 connects the top of the heating chamber :to a cooling toweror waste pipe. A by-pass conduit 86 connects conduits 40 and 85 and athrottling valve 87 at the junction of conduits 40 and 86 regulates theflow of cooling uid through the by-pass. When the valve 87 is closed all0f the cooling fluid from the condenser will ow through the heatingchamber 83 in heat exchange relation with the coil S2. When the valve isfully open substantially all of the fluid will liow through the by-pass86. At any intermediate positions of the valve 87 the uid will iiowproportionately through the heating chamber 83 and by-pass 86,respectively. Valve 87 is controlled by a thermostat having a bulb S8responsive to the temperature of the air in the enclosure 8, a bellows89 connected to open valve 87 and a spring 90 opposing bellows 89 foractuating the valve toward closed position.

The arrangement illustrated in Fig. 3 operates to heat or cool the airin enclosure 8 in the same way as the arrangement illustrated in Fig. 1and described above. When dehumidication without cooling is desired theair to be conditioned is precooled by the fluid in heat exchange coil 42and the heat removed is delivered back to the air by the reheat coil 43.However, in the embodiment of the invention illustrated in Fig. 3, the.additional heat is supplied to the circulating fluid by the heatexchange element utilizing waste heat from the refrigeration system. Tothis end, cooling water from the condenser 19 is delivered throughconduit 40, heating chamber 83 of heat exchange element 80 and `outletconduit 85'. The relatively warm cooling water, for example, F., flowsin heat exchange relation with the fluid in coil 82 at 73 F. to supplythe additional heat to the uid. When the temperature of the circulatingair increases, valve 87 is operated to divert a portion of the coolingwater from the condenser 19 through the by-pass conduit 86 to decreasethe amount of heat added in the heat exchange element 80. As thetemperature of the air decreases, the valve S7 is operated to decreasethe amount of uid owing through the by-pass 86 and increase the amountof uid owing through the heating chamber 83, Thus, the control S1operates to vary the amount of heat added to the closed heat exchangesystem in accordance with requirements to maintain a substantiallyconstant air temperature in the enclosure 8.

It will now be observed that the present invention provides a closedheat exchange system adapted to heat the air in the winter and cooperatewith the cooling element to dehumidify and reheat the air in the summer.It will also be observed that the present invention provides a heatexchange system of the type indicated which operates to dehumidify theair at a high rate and deliver air back to the enclosure withoutdecrease in temperature. It will also be observed that the heat exchangesystem of the present invent-ion precools air prior to dehumidiiicationand utilizes the heat removed from the air to reheat the air afterdehumidication to reduce the load on the refrigeration system. It willstill further be observed that the present invention provides a reheatarrangement which utilizes waste heat from the refrigeration system toincrease the overall thermal eciency of the air conditioning unit anddecrease the load on a cooling tower when used.

While two embodiments of the invention are herein illustrated anddescribed, it is to be understood that further modications may be madein the construction and arrangement of elements without departing fromthe spirit or scope of the invention. Therefore without limitation inthis respect, the invention is detined by the following claims.

I claim:

l. In an air conditioner, conduit means providing a conditioning chamberthrough which a stream of air passes, a heat operated refrigerationsystem having a cooling element in the chamber, a heating systemcontaining a heat exchange tluid and having a heat exchange section inthe chamber at the front of the cooling element in the direction of theair stream, a heat exchange section in the chamber at the rear of thecooling element, a heat exchange section outside the air stream,conduits connecting the sections to provide a closed run-around circuit,means for circulating the fluid through the heating system, a source ofheat, and selective means for delivering heat from said source to therefrigeration system or the heat exchange section of the heating systemoutside the air stream or to both the refrigeration system and heatexchange section of the heating system simultaneously.

2. In an air conditioner, a path for air to be conditioned, means forowing air through said path, a heat yoperated refrigeration systemhaving a cooling element in the path of air llow, a heating systemproviding a closed circuit for a heat exchange fluid and comprising aheat exchange section in front of the cooling element in the path of airflow, a heat exchange section at the rear of the cooling element and aheat exchange section `outside the path of air llow, means forcirculating the heat exchange fluid through the heating system, a sourcef heat, selective valve means for delivering heat from said source tothe heat operated refrigeration system or heat exchange section of theheating system remote from the cooling element, a by-pass around thevalve means for supplying heat to the refrigeration system and heatingsystem simultaneously, and auxiliary valve means in the by-pass forregulating the amount of heat supplied from said source through thebypass.

3. In an air conditioner, an air conditioning chamber, means forcirculating air through the chamber, a heat operated refrigerationsystem having a cooling element in the chamber, a heating systemproviding a closed circuit for a heat exchange lluid and having a heatexchange section in the chamber at the front of the cooling element inthe direction of air flow, a heat exchange section in the chamber at therear of the cooling element in the direction of air llow and a heatexchange section outside the chamber, means for circulating the heatexchange lluid through the heating system, a source of heat, selectivevalve means for delivering heat from said source to the heat operatedrefrigerati-on system or heat exchange section of the heating systemoutside the chamber, a by-pass around the valve means for supplying heatfrom said source to the heating system simultaneously with its supply tothe refrigeration system, a

throttling valve in said by-pass, and means responsive to thetemperature of the circulating air for controlling the throttling valvein the by-pass to regulate the amount of heat supplied to the heatingsystem.

4. In an air conditioner, a heat operated refrigeration system having alow temperature cooling element and a high temperature heat rejectingelement, a heating systern providing a closed circuit for a rst heatexchange fluid and having a first heat exchange section in front of thecooling element, a second section at the rear of the cooling element anda plurality of sections remote from the cooling element, means forcirculating air through the first section, cooling element and secondsection of the heating system in succession, means for circulating theheat exchange fluid through the plurality of remote sections, the secondand rst sections of the heating system in succession, a source of heat,selective valve means for directing heat from said source to the heatoperated refrigeration system or one of the remote heat exchangesections of the heat-ing system, respectively, means for circulating asecond heat exchange lluid in heat exchange with the heat rejectingelement 4of the refrigeration system and other remote section of theheating system, and means responsive to the temperature of thecirculating air for regulating the amount of the second heat exchangeluid delivered from the heat rejecting element of the refrigerationsystem to the heat receiving element of the heating system.

References Cited in the le of this patent UNITED STATES PATENTS Re.22,100 Brace May 26, 1942 2,094,221 Shaller Sept. 28, 1937 2,112,520Crawford Mar. 29, 1938 2,200,118 Miller May 7, 1940 2,216,475 MetcalfOct. 1, 1940 2,244,551 Crawford June 3, 1941 2,257,975 Miller et al Get.7, 1941 2,286,605 Crawford June 16, 1942 2,304,243 Crawford Dec. 8, 19422,352,930 Anderson July 4, 1944 FOREIGN PATENTS 468,931 Great BritainJuly 15, 1937

